For those of you that have followed my meanderings on upgrading my Decware amp, I've decided to split the project into two phases. The second phase will be the fully decked and tricked SE EL84, with an EF86 input stage,transformer coupled, and with a super duper power supply. However, after starting to read Rozenbilt and Morgon Jones, I've got a good year of studying to do before I'm comfortable tackling that project. However, there is no way I'm not going to sling some serious solder before then. So now comes phase one.

I will upgrade my current SE84CSEX as follows.Both grid stoppers(330 and 1K) will be 330 ohm Shinkohs, The coupling cap will be a Mundorf silver/gold, cathode bias on sv83 will be kiwame, on 6922 will be riken. the 47k plates and 330k grid leaks will be rikens. The 100k pot goes, replaced with a Riken(value tbd). All the PSU caps will be ASC oil caps. The 40 uf will be replaced as is, the two 20 ufs with a single 10 uf, and the two 3.3s with 4 uf caps. I'm figuring the sonic priorities are first the coupling cap, then the grid stoppers,then the cathode bias resistors, then the PS, then the plate resistors, then the grid leaks. So heres the question.

Clearly, it would be easier(and safer) to do everything at once. However, if it would be helpful to you guys, I would do each upgrade separately and report on what I heard from each step.

So, let me know what you all think. If noone cares, I'll do it all at once and of course report back. If there's an interest, I'll do it piece by piece and report back. Let me know your preference and also what you think the modification order should be. I would probably do the PS caps last, as that will require chassis modifications.

Eddie gave me great insight on the two 20s vrs the single 10, which is why I'll be changing to the single 10 uf cap in the PS. But I'd rather not state those reasons myself and let Eddie explain to all himself, which I hope will be forthcoming shortly. Where are you Eddie? My other posts are begging for answers. I hope you're feeling better :D

you could always upgrade all the power supply 'lytics to Solen Fast Films, (that I've tried - not subtle) or even PIO motor runs (not yet, but guess whose suggestion that was?)

Of course, as has been stated many times before, mods or tweaks this extensive really amount to a complete change in overall voicing and flavour of the amp. Good thing there's enough tolerance in the "subjective evaluation / system tailoring" process to allow for any changes to the original to still be vaild to our own ears.

The ASC caps I mentioned are PIO motor runs made by American Shizuki Corp. I've already got the two 40 ufs in hand, but I'm having trouble sourcing a single 10 uf and two 4 uf caps. I think you can quess whose advice I followed on these babies( they are big-WILL NOT fit inside the regular chassis). If any of you know of a source for the smaller values, your help would be most appreciated.

FYI, Angela Instruments(most expensive), Parts Connexion, and Michael Percy carry the larger values. Parts Connexion may be able to order the 10 and 4 uf values with a minimum quantity. I'll know early next week what that minimum is. If it's not outrageous, maybe this forum can do a group buy, which I'll organize. After I get the info, I'll see if there's any interest. ( You know who's description of the sound of these babies has me salivating)

I just can't find a vendor who sells the smaller values. The smallest I've been able to to find has been the 15uf. I'm wondering if the smaller values are being used by specialty maunfacturers and aren't available to general distributors. I'll keep trying.

[quote author=crazy bill the eel killer link=1134529794/0#12 date=1134836855]Thanks for the links. I'll have to investigate them. Get you know who's opinion on them sonically. [/quote]

???Gee, who could that be?

Well, I would want to track down the ASC's for the sake of consistancy and for their reputation. I'm anxious to hear how your project turns out. I would be interested in hearing your impressions for each and every change, but realize that it's just too time consuming.

I've re-built my amp using the same resistor combination you're planning and love the sound. I went with the V-Caps and can whole heartedly recommend them. I am curious about the Mundorfs though.

Are you planning to use cathode bypass caps on the input tube? If so Black Gate? I'm running a pair of 47uF there and really like the fuller sound they provide. I've been wondering what replacing them with a 50uF ASC oiler would sound like. Man that would be a BIG chassis though. All for a whopping 2 watts, but glorious watts none the less.

I've thought about a cathode bypass cap, but I haven't done the math yet to see whats needed for a 1hz pole. I will not put any electrolytics anywhere, but if the value figures reasonable enough to use a motor run I'll try it and see. It will eliminate the degenerative feedback that occurrs with an unbypassed cathode bias resistor, which should slightly increase the gain of the input stage and provide a little more pop, which to me is a good thing, and your listening seems to bear out.

I've thought about the V-cap, and I really think, based upon reviews and opinions of people I respect(guess who), that I would prefer it, but that 400 hour break-in scares the hell out of me. I suppose I could put a dummy load on the amp and let it go continuously for a few weeks. I may do that yet.

I've got to get a couple of things cleared up, but I probably will build a whole new amp instead of bastardizing my Zen. It's all up to what you know who has to say on a couple of burning questions. Since I've got different output iron it just makes sense.

I won't be starting until the new year, but I'll post pictures and commentary as the project progresses.

Simply put you never hear the fidelity of a given system rise past it's weakest link.

Zen amps are so transparent that you will hear large differences in cables - well beyond the norm.

We manufacture cables that allow you to hear how good the amps actually are. Both the interconnects and speaker cables are comparable to retail products in the 4 digit price range, but of course are sold at what they actually cost to make. Again our perspective is that we want you to hear how good our amps actually are and know your not likely to spend the 2 grand or more on cables to find out.

My suggestion is start with interconnects, buy the DSRII's on the 30 day trial and find out for yourself.

Don't be in such a hurry to bypass the voltage gain triode's cathode resistor. The local current NFB linearizes the block. If a little more gain from the voltage amplifier is something you're looking for, consider using the 5965 instead of the 6922. The 5965 is a NICE tube, with a mu of 44.

Also, there are 'lytics and there are 'lytics. Gordon Rankin uses non-polar Black Gates as cathode resistor bypasses. 'Nuf said.

Thanks for the advice. I don't plan to do anything hasty. The cathode bypass cap experiment will be just that, and the final arbiter will be my ears. You are of course completely correct about the Black Gates. I've never heard an A/B done against anything else, but the manufacturers who use them in their products is enough of an endorsement for me. I've been trying to read a lot about capacitors and the details of their construction, and I think that generally, properly constructed and implemented film/foil or paper/oil, should outperform any electrolytic. But the proof's in the pudding, so they say, so the only real way to tell is to implement and listen. I would love to conduct such a test(Black Gates/PIO), but the cost of those items, and the fact that I may like the sound better w/o them, keeps that off my wish list.

As far as the gain of the first stage is concerned, I don't necessarily need to increase it. I've changed my tube compliment, and I'm now using a Valve Art 274b rectifier. I did have an issue w/ a few sources and gain, but it's gone now that I'm using that rectifier. Don't know why that should be. I should probably look at the spec sheets and see if maybe the voltage drop across the 274b is less than the Ruby. Maybe I'm juicing the amp a little higher. I know I like the way it sounds with the VA274b WAY BETTER.

I'm doing this project piecemeal so I can listen after each step. I don't want to change the values of any component, so that the changes(if any) that I hear are strictly due to the nature of each component. Its a learning curve for me. I like the way Steve voiced this amp, but the only way I'm going to learn is to play.